In the electrical alimentation of vehicle field, in particular for electrically propelled vehicles, it is known to provide the vehicle with an autonomous power supply device, such as a battery or some capacitors, an electric connection member, such as a pantograph, and a power supply bus which electrically connects the pantograph and the battery to an electric motor of the vehicle.
Thus, it is known to use an electrical power supply system, including an external power supply zone and an autonomous power supply zone. The vehicle is supplied in the external power supply zone by means of an external power supply infrastructure, such as a catenary line. The pantograph realizes the electrical contact between the catenary line and the power supply bus of the vehicle. Once the pantograph is connected to the catenary line, an electric current flows between the catenary line and power supply bus of the vehicle.
On the opposite, when it is in the autonomous power supply zone, the vehicle is supplied by means of the autonomous power supply device.
However, while the vehicle is moving from a power supply zone to the other one, in particular in the instant when the pantograph is connecting or disconnecting from the catenary line, an electric arc is generated between the catenary line and the pantograph, as the electric current flowing between them does not extinguish instantaneously. The electric arc generated between the catenary line and the pantograph should be avoided since it may provoke detriments of the catenary line and of the pantograph, as well as a remarkable electromagnetic noise.
As explained in WO-A-2011/147708, it is therefore preferred to equip the power supply bus of the vehicle with an electrical protection device, such as a diode, which allows the electric current to pass only from the pantograph to the power supply bus of the vehicle. In other words, the diode mounted on the power supply bus of the vehicle is continuously crossed by the electric current of the catenary line for the power supply.
This approach leads to some technical inconvenients. First, the diode needs to be continuously cooled down by a proper system placed in the vehicle, in order to keep the right operating temperature. Second, the diode blocks any current flowing from the power supply bus towards the catenary line, which means that no electrical braking regeneration can be performed.